प्राचीन भारत में 'द्वितीय नगरीकरण' में किस धातु ने महत्वपूर्ण भूमिका निभाई थी?

Gautama Buddha was born at ______.

Consider the following statements regarding a historical period: (i) Animals began to be used for transporting goods during this period. (ii) Trade and transportation developed significantly in this era. (iii) Pottery making using the potter's wheel started in this age. Which historical period is described by the above statements?